This
concept of storing a file as a set of blocks is very consistent with how a
normal file systems work. But what the different about HDFS is the scale. A
typical block size that we would see in a file system under Linux is 4KB, whereas
a typical block size in Hadoop is 128MB. This value is configurable, and it can
be customized, as both a new system default and a custom value for individual
files.